Lexicon MPX 500 - General Troubleshooting and Service Notes; Power Supply; Front Panel Knobs; Lexichip Replacement

MPX 500 Service Manual
5-8
One is for the factory. Once the unit is manufactured and tested it is placed in this burn in loop over a period
of time to exercise the main circuitry and verify the unit is performing to manufactured specifications.
The second is for in field repair. It allows you to exercise the circuitry after repairs have been made. Again
this is to insure the performance and specification of the MPX 500.
During the execution of the Diagnostics in the Burn In loop, the appropriate test code will be displayed on
the Binary LED’s (BYPASS, STORE & TAP). This code will be sent to the LEDs before each test is
executed. By displaying a test/error code on the LEDs before the test is activated, it will be easier to
determine which test failed if the unit hangs or crashes during the Burn In loop. The test numbers and
names are also displayed on the LCD Display, along with the Pass/Fail status of each test.
When the test is
executed, the LCD Display will indicate the test is “Running…” followed by the Pass/Fail status of the test.
The following table shows the tests run in the Burn In Test.
Test
Number
Test
Name
Bypas
s
LED
Store
LED
Tap
LED
LCD
Display
1ROM 001ROM
2 SRAM 0 1 0 SRAM
3WCS 011WCS
4INT 100INT
5ADF 101ADF
7 DRAM 1 1 1 DRAM
0 = OFF
1 = ON
General Troubleshooting and Service Notes
Power Supply
• CAUTION: There is no protective paper covering power supply, IEC connector or power switch leads.
Beware of exposed line voltages.
• The power supply module should not be repaired. The entire module should be replaced if failure
occurs.
Front Panel Knobs
• It is difficult to remove the knobs on the front panel without causing damage to the either the knobs or
front panel. Extra knobs should be kept on hand for repair needs.
Lexichip Replacement
• The Lexichip requires a heatsink that is installed with a thermal epoxy. The parts list contains the P/N
for replacement heatsinks and the proper adhesive. Keep replacement heatsinks and adhesive on hand
for repairs. Adhesive should be epoxy, thermally-conductive and equivalent to:
• Aavid Thermal Technologies part number
• 161000F00000 (10 gm) or
• 164000F00000 (40 gm)